Friday, February 27, 2009

Plotting PDQ Output with R

One the nice things about PDQ-R (coming in release 5.0) is the ability to plot PDQ output directly in R. Here's a PDQ-R script, together with the corresponding graphical output, that I knocked up to show the effect on the throughput curve of adding more queueing delay stages (K), with everything else held constant.

Sunday, February 22, 2009

PDQ-R Lives!

After some fiddling to get things linked correctly to the R binaries on my new Macbook, the first PDQ-R test model has run successfully! Here 'tiz ...

This is an important step for PDQ development and is due entirely to the efforts of Phil Feller. Naturally, this capability will be included in the next PDQ release from SourceForge, which we are currently working towards. Stay tuned!

Tuesday, February 17, 2009

Guerrilla Boot Camp Training

Registration for my local Guerrilla Boot Camp classes is still open. The first checkpoint is coming up on Feb 26th. That's when we need to notify the hotel whether or not we're going ahead. So if you're thinking of coming, be sure to enroll soon and don't leave it until the last minute.

Overseas attendees are welcome. Check out your exchange rate against the Yankee greenback.

In a related item: Survey says, "Online Instruction is Less Effective Than Classroom Learning."

Apdex Index Examined

This month's edition of the CMG MeasureIT open-access journal has 2 articles on the Apdex Performance Index:
  1. "The Apdex Index Revealed", by yours truly
  2. "The Apdex Index vs Traditional Management Information Decision Tools", by Jim Brady
Jim's article compares the Apdex Index with other well-established management decision techniques; especially those based on statistical methods. As someone with a background in Operations Research, Jim is well placed to make these assessments. It's worth noting that Jim's paper arose out of PARS discussion he and I had at CMG'08 in Las Vegas. PARS stands for Performance Analysts' Relaxation Session (a play on mainframe LPARS) but most CMG-ers just think of it as a "free" food and booze session. ;-) I was relating to Jim that I had attended a couple of CMG presentations which tried to explain the deeper significance of the Apdex Index definitions and there were a few things that really bothered me. I thought he might be able to explain it to me in terms of mathematical statistics. We didn't resolve anything that night (what can you expect with all that booze around?), so I left it with him as homework. His paper is the outcome. You'll have to read my article to find out what was bothering me. :-)

Friday, February 6, 2009

Dr. Dobb's is Dying

My colleague Jim Holtman just informed me that, according to, the illustrious software developer magazine Dr. Dobb's Journal will now be embedded(pun intended) in InformationWeek. Both are owned by United Business Media LLC.

Jim and I have been following the series of articles by Herb Sutter on multicore concurrency, starting with the one entitled "Break Amdahl", where he discovers Gustafson's law (see Section 4.3.5 of my GCaP book, Springer 2007). As expected, that title looks slightly optimistic in light of the recently observed lack of scalability on Sandia Labs supercomputers. Of course, the universal law of scalability accounts for all these effects and, unlike Sutter's articles, we are able to quantify them based on actual measurements.

Anyway, as with print newspapers, I suppose all this means that even though Dr. Dobb's is not exactly dead yet, it is getting buried alive.

Sunday, February 1, 2009

NorCal CMG Meeting Location

For those of you who haven't attended before, the Feb 3rd (Tues) meeting of the Northern California CMG will be held in Suite 100 of the Compuware building in Pleasanton, California. Here's the Google map. Three talks will be presented:
  • 9:30--10:30 Mongo Measurement Requires Mongo Capacity Management, Neil Gunther, Performance Dynamics Company
  • 10:45--11:45 Wasted MIPS, Wanton MIPS: a MIPS Recovery Initiative, Tom Halinski, Compuware Corporation
  • 1:00--2:00 The Apdex Index Revealed, Neil Gunther, Performance Dynamics Company

Breakfast starts at 8:30 am and registration is $25 at the door.

Poor Scalability on Multicore Supercomputers

Guerrilla grad Paul P. sent me another gem in which Sandia scientists discover that more core processors don't produce more parallelism on their supercomputer applications:
"16 multicores perform barely as well as 2 for complex applications."